Basically keep in mind that pistons are cheep (>$100 dollars), cylinders are more expensive (>~$250 to get replated) and cranks are about the same price as cylinders, but much harder to install. With a professional installation if you bring them the motor a crank will run you about 600-800 dollars. Without taking the bike apart it will be very dificult to determin the extent of the damamge. Presumeably the bike is either locked up or has no compression. If its locked up then it is likely that at the very least the cylinder is scored and will need to be replated (I think its a plated cylinder, not steel sleeved, but not 100% sure) and its reasonably likely the bottom end was damaged as parts of the piston could have made their way down into the crank bearings or the rod coud have bent when the pistion seized. If the bike is just low on compression it is likley that you could get buy with just a top end.
things to check when looking at the bike (assuming you can't pull the top end off at this time)
- Chassie bearings, is there much play in the rear suspension linkage, steering head bearings, wheelbearings etc?
- suspension, do both ends move up and down smoothly when you push on the bike? Is there any sign of oil leakign from the fork or shock seals?
- does the bike look like its been maintained (clean, chain properly adjusted, air filter clean, antifreeze clean etc?
- Transmission (assumeing the engine is locked up). Put the bike on a stand and see if the rear wheel spins in neutral (it should). shift through the gears (you will probably have to move the rear wheel to get it to shift, once in gear the rear wheel should not spin). It should have 5 gears not including neutral.
Considering that the bike was stolen, it is likely that the bike was run without pre-mix, which means that it most likely will need a top and bottom end.
good luck:)
